A modern vehicle, such as a car, is provided with safety arrangements in order to prevent or avoid
It is well-known to use a safety arrangement comprising a seat belt for restraining the movement of the seat occupant in case of a sudden change of speed of the vehicle. Yet, a modern seat belt permits the seat occupant to move during normal driving conditions or when the vehicle stands still by adjusting the used length of the seat belt according to the movements of the seat occupant, e.g., when the seat occupant leans forwards.
It is known to use a retractor to suddenly and forcefully retract the seat belt in case of a collision or imminent collision being detected, since it is beneficial for the seat occupant to be located close to a seat back and a headrest in such a situation. The sudden and forceful retraction of the seat belt may be uncomfortable for the seat occupant, and may even cause a minor injury to the seat occupant. However, the advantages of being seated close to the seat back and headrest in case of a collision outweigh any discomfort or minor injury.
It is also known to reposition a seat or a portion of the seat, e.g., the seat back, in order to bring the seat occupant into a more favorable position in case of a collision or imminent collision being detected. Purely as an example, if the seat back is inclined backwards, it may be beneficial to move it to a more upright position, e.g., in case of a rear-end collision.
Document EP 1 454 806 A2 discloses a device, which regulates or controls an occupant restraint system of a motor vehicle in dependence on a pulling force acting on a seat belt. The force is measured between a subassembly anchored to the vehicle structure and another subassembly that is movable away from the first subassembly. Force measurement signals are evaluated by an evaluating device for the setting of at least one restraint function of a vehicle occupant restraint system during normal driving conditions, during a pre-crash condition or during a crash, in a computer-assisted manner.
Document EP 1 454 806 A2 describes the above-described use of a refractor to suddenly and forcefully retract the seat belt in case of a collision or imminent collision being detected as well as to reposition a seat or a portion of the seat in order to bring the seat occupant in a favorable position. However, if performing both the retraction and the repositioning at the same times, as is described in document EP 1 454 806 A2, there is a risk that a seat occupant may be exposed to such a high seat belt force, that it may cause discomfort to the seat occupant or even an injury, e.g., breaking a collar bone or a rib.